1. Field of the Invention
The present invention relates to dispensing devices in general.
More particularly, the invention relates to dispensing devices for dispensing two or more substances.
Specifically, the invention is directed to a device for dispensing two or more substances in different percentages.
2. The Prior Art
There are instances when it is desired for a dispenser to be capable of dispensing two or more substances (e.g. liquids, syrups, flowable powders or granules, pasty substances and the like) in certain ratios. A particular application is for dispensing of two-component compositions, for example, polyester and catalyst therefor which, when mixed in a certain ratio immediately prior to use, yield a composition used in the repair of automobile bodies. A prior art device for this purpose, the only one known to be on the market, has a base, a U-shaped pusher element with parallel legs the free ends of which push against the mobile bottom walls of two containers, and a system for advancing the pusher element towards the mobile bottom walls. These bottom walls are then each pushed towards stationary other bottom wall of the respective container, which results in the simultaneous expulsion of the two substances from the outlets of the two containers. The advancing system includes a movable rack for the pusher element and a pawl which cooperates with the rack and is operated by a lever driven by movement of a handle.
One of the most important disadvantages of this prior-art device is the fact that the ratio of one dispensed substance to the other (i.e. their percentages) is fixed and cannot be changed. Often, however, it is desired to be able to change this ratio; in fact, in many instances it is necessary to be able to do so to compensate for changes in ambient temperature and/or because of other reasons.
In the device known from the prior art, the operating lever must be moved by hand and its motion is transmitted to the movable bottom walls of the two containers. The volumetric content of the containers is therefore restricted to about 1.5 kg since the average human hand does not have sufficient strength to overcome the resistance offered by larger containers. Also, there is no way to continuously adjust the dispensing of the substances; the pusher system can move only in increments of one tooth of the rack. Accordingly, the quantity of the two substances being dispensed is always the same; it cannot be made smaller, nor can it be made larger than the predetermined amount except in whole multiples.
A further disadvantage of the prior-art device is that quite often at the beginning of the dispensing operation only one of the two substances will be discharged, and that the discharge of the other substance starts somewhat later. This changes the predetermined ratio of the two substances in the dispensed product. As a result, the product may have to be discarded. At the very least, that quantity of the sole substance which was dispensed before dispensing of the other substance began, has to be thrown away.